1. Field of the Invention
The present invention relates to a racket stringing machine and, more particularly, to a racket stringing machine which is provided with a horizontal adjustment device capable of improving stringing quality by adjusting the left and right positions of the string pulling device and a brake device allowing the operator to leave or stop the stringing machine for a while during the stringing operation.
2. Description of the Prior Art
Referring to FIG. 1, a conventional racket stringing machine is shown and comprises a base a, a frame retainer b and a string pulling device c. The frame retainer b is pivotal upon a rotary shaft in the top of the base a and can be rotated and positioned thereon. The string pulling device c includes a pulling member c1 and a rotary member c2 and is connected to the base a via a horizontal plate 10 located at the top of the base a. The horizontal plate 10 is provided with a ratchet 101 along which the string pulling device c moves, namely, the string pulling device c is movable along the horizontal plate 10.
In operation, as shown in FIG. 2, a racket frame d is retained on the frame retainer b. The string e is then fixed between the pulling member c1 of the string pulling device c and the racket frame d of the racket. After that, a desired string tension value is set, and rotating the rotary member c2 can adjust the string tension of the string e to the desired value. By repeating the above operation, the lengthwise and transverse strings e can be strung to the racket frame d, respectively.
Although it can perform the stringing operation automatically and conveniently, this racket stringing machine still has the following disadvantages:
1) the horizontal plate 10 and the string pulling device c are fixed at the same position without being able to move, and the strings e must be pulled one by one. Hence, from a top view, there can be seen an angle θ between the outer periphery of the racket frame d of the racket and the strings e, and this angle still exists even after the racket frame d of the racket rotates. Therefore, during the stringing operation, the force distribution on the racket frame d of the racket is non-uniform, resulting in an inaccurate tension of the strings e. On top of that, there will be friction between the inserting holes of the racket frame d of the racket and the strings e, which will probably damage or even break the strings e. Even if the strings e are not broken after stringing, the structure of the racket frame d of the racket will be adversely affected. It greatly reduces the life of the racket and the strings e. Furthermore, the imprecise string tension may affect the performance of the player using the racket.
2) this racket stringing machine should be operated by an operator on the spot, and during operation, the operator may have something urgent to deal with and have to leave for a while. However, once the stringing process begins, the racket stringing machine must keep running continuously until the stringing of the whole racket is done. Otherwise, the strings e in the process of being pulled through the racket frame d of the racket will loosen once the stringing machine is turned off. After the stringing machine starts running again and after it finishes the stringing operation, the strings e will be loose, and the racket cannot be used, so the stringing operation must be started all over again. Thus, it is quite time consuming.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.